Senator John McCain (R) of Arizona speaks at the 2010 meeting of the Wall Street Journal CEO Council in Washington, Nov. 15. A bipartisan group of four US senators, including John McCain, announced Tuesday that they’ll push for a vote on a plan to ban earmarks.

“Earmarks are not only wasteful but are terrible distractions for both parties. The sooner we get rid of earmarks the sooner we can go to work on the difficult task of getting our budget under control,” said Senator Coburn in a statement on the group’s effort.

This hands-across-the-aisle move is only the latest in a series of things indicating that earmarks, or pet projects of lawmakers, may be about to end. Senate minority leader Mitch McConnell (R) of Kentucky, a longtime defender of earmark spending, has switched sides, for instance, and now supports a ban. So does President Obama.

In the short run an earmark ban, if it passes the House and Senate, would certainly cut back on the practice. The press would give extra scrutiny to appropriations bills to see what they contained – as would lawmakers’ own colleagues, since they would not want someone else to cheat and sneak something through.

But remember, a ban isn’t yet a sure thing – Democrats maintain a bare majority in the Senate, and majority leader Harry Reid (D) of Nevada remains a proponent of the practice.

“I have an obligation to the people of Nevada to do what is important for Nevada,” Senator Reid said Tuesday.

Even some lawmakers who support the ban are kind of hedging. Sen. Lamar Alexander (R) of Tennessee issued a statement Tuesday in which he backed the vow of the Republican caucus to enforce an earmarks moratorium on its members. But he added that “I reserve the right to ask Congress and the president to approve measures of urgent importance to Tennesseans.”

Sen. Lindsey Graham (R) of South Carolina went even further, saying in a statement that “I respect the spirit in which this moratorium has been agreed to and hope it will lead to a better use of taxpayer dollars. However, I maintain the right to seek funding to protect our national security of where the jobs and economy of South Carolina are at risk.”

And what, really, constitutes an earmark? Most are not in appropriations bills at all. They are included in the plain-language reports Congress produces along with legislative legal language, and they direct the executive branch to spend certain funds in ways that benefit a particular state or district. But there are other ways to accomplish that purpose of channeling money without using earmarks, per se.

Senator Udall, for instance, is one of the four senators pressing for a binding vote on earmark exclusion. But in a broadcast interview Tuesday on MSNBC, he said that even without earmarks “there are plenty of other ways I can support what my state needs.”

“I have a staff person who’s dedicated to working with colleges, with universities, with nonprofits, with for-profit companies that want federal funding. That’s the way to send federal dollars into the states,” said Udall.

And on Wednesday morning, the lead story on Senator McCaskill’s official website was the amount of federal stimulus funds that would be flowing into Missouri for high-speed rail, and the jobs this cash might generate. That story disappeared about 11:30 a.m., replaced by the announcement of McCaskill’s participation in the effort to ban earmarks.

McCaskill is far from unusual in this regard, as many, many US lawmakers highlight similar accomplishments for their constituents. The point is that while specific-language earmarks might be banned, it is much more difficult to ban the desire for federal funds within states, and the political pressures that generates.